Sleeping Bag ???

I also agree about down. My next bag will be down. The Valandre Bloody Mary is high on my list. I have plenty of synthetic bags to use if space is not any issue. All my down bags have been warmer, lighter, and pack smaller. My experience has been the same as many mountaineers; the vapor from your body heat condensation on the outside of the bag during very cold nights. Eventually it continues to build up until your bag is completely soaked. I don't have a problem unless it's very cold. I now use a vapor barrier liner, which you can make yourself, or buy from places like REI. No more wet bags. This keeps me from waking up in the middle of the night freezing because my bag is wet. I won't go out in sub 0 temps with any bag, and especially a down bag, without a vapor barrier liner.

I have a AF issue down bag. It is heavy and bulky and I have never use it in cold weather backpacking/hunting. I use a relatively cheap but well made poly filled bag with a rating of maybe 20*. I can sleep comfortably down to zero degree wether by wearing merino wool thermals, ski socks and cap.

It's true that the chances of a down bag getting saturated wet in cold weather is slim, but if it does happen.... and you are a long way from the truck... you are dead... unless you have a buddy with a dry bag. You could build a fire and stay by it if it's not raining, or you could put your headlamp on and start hiking out all night. Water can be fairly effectively squeezed out of poly fill bags and they will reatain most of their loft (dead air space) which is were they (and down) get their insulation value. It's not the wetness that kills the insulation value, it's the lack of loft. Water can be heated by body heat.

Although down has a lot of appealing qualities... for this reason... I will always take a poly filled bag into the backcountry with me. And I can reduce it's weight by wearing very comfortable med weight (lighter than cotton thermals) merino wool thermals which will also maintain their insulating qualities in wet conditions. Not a bad idea to have second pair of thermals along in backcountry, cold weather conditions.